clear,clc;
syms r,x1,y1,m1,m2,m3,m4,a,b,c;
r=1;d1=1;
x1=r,y1=0;
x2=r+m1*cos(a),y2=m1*sin(a);
x3=r+m1*cos(a)+m2*cos(a+b),y3=m1*sin(a)+m2*sin(a+b);
x4=r+m1*cos(a)+m2*cos(a+b)+m3*cos(a+b+c),y4=m1*sin(a)+m2*sin(a+b)+m3*sin(a+b+c);

